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Repairing milling attachment for Craftsman/atlas lathe

Last night I made a craigslist purchase of an old craftsman 12" lathe just so I could get some of the accessories. One of them was the factory milling attachment. After I got home and was making a close inspection of my haul, I noticed a slight bulge below each of the retaining pins indicating that sometime in the past the mill was forced against the pins and cracked the cast iron around the holes out....

Just curious how I should go about fixing this? Any ideas? My first thought is to just knock out the broken parts, weld, machine, and re-drill the holes, but my cast iron experience is limited to knowing that it can be tricky stuff....

Having no picture to help me fully understand the problem, I'll offer the following experience.

I obtained an Atlas MF Mill with vise. Upon cleaning up the vise i discovered that at some point the fixed jaw had bee broken off and repaired with brazing. So far this repair has worked well and not shown any signs of breaking again. With common sense use it will probably be fine for as long as I want the Mill.

So, that all said, perhaps brazing would be an acceptable repair for your issue.

The pin and taper system isnít up to the task. Even with parts that are in perfect order you will see movement - oil pumping from this joint. Drill and tap a .375 ish thread in the cross slide stud and drill a corresponding clearance hole through the center of your attachment between the gussets. Relieve the high spots and bolt the attachment on with a SHCS or a bolt with spacer. A piece of thin paper, phone book page, between the parts will ensure that nothing slips without the need to gorilla tighten them. This modification yields such good results that it is worth doing to undamaged parts, so you might consider doing both of them while you are at it. Having a threaded hole in the stud makes it much easier to rigidly mount other fixtures.
One more point, this modification is also the cure if your lathe or the attachment has been used a lot as the attachment will want to return to the worn spots, from previous use, on the stud taper and this can make it very difficult to properly tram for your setup.
Donít apply heat!
Good luck, Mike

Mike,sounds like a great mod. Any chance of getting a picture of this mod. I think a lot of us will be doing this. Thanks! Eric

Originally Posted by mf205i

The pin and taper system isnít up to the task. Even with parts that are in perfect order you will see movement - oil pumping from this joint. Drill and tap a .375 ish thread in the cross slide stud and drill a corresponding clearance hole through the center of your attachment between the gussets. Relieve the high spots and bolt the attachment on with a SHCS or a bolt with spacer. A piece of thin paper, phone book page, between the parts will ensure that nothing slips without the need to gorilla tighten them. This modification yields such good results that it is worth doing to undamaged parts, so you might consider doing both of them while you are at it. Having a threaded hole in the stud makes it much easier to rigidly mount other fixtures.
One more point, this modification is also the cure if your lathe or the attachment has been used a lot as the attachment will want to return to the worn spots, from previous use, on the stud taper and this can make it very difficult to properly tram for your setup.
Donít apply heat!
Good luck, Mike

"Patriotism is supporting your country all the time, and your government when it deserves it". Mark Twain

I'm not sure what "pin" you're talking about. The picture below shows the Atlas Milling Attachment. The only pins I know of are the beveled pins that fit against the swivel when you pull the compound off to mount the attachment.

The pin and taper system isnít up to the task. Even with parts that are in perfect order you will see movement - oil pumping from this joint. Drill and tap a .375 ish thread in the cross slide stud and drill a corresponding clearance hole through the center of your attachment between the gussets. Relieve the high spots and bolt the attachment on with a SHCS or a bolt with spacer. A piece of thin paper, phone book page, between the parts will ensure that nothing slips without the need to gorilla tighten them. This modification yields such good results that it is worth doing to undamaged parts, so you might consider doing both of them while you are at it. Having a threaded hole in the stud makes it much easier to rigidly mount other fixtures.
One more point, this modification is also the cure if your lathe or the attachment has been used a lot as the attachment will want to return to the worn spots, from previous use, on the stud taper and this can make it very difficult to properly tram for your setup.
Donít apply heat!
Good luck, Mike

I'd considered brazing but I was concerned it might not be strong enough.

Don't underestimate the strength of a properly done braze joint, it most likely will be nearly as strong, or even AS strong, as the original cast iron. If you do decide to weld this thing brazing would probably be a much better way to do it than arc welding with Nickle rod.

The stud he is referring to is the dovetailed boss sticking up from the cross-slide, to which the milling attachment or compound clamps. You drill and tap this for that bolt which goes vertically through a new hole in the milling attachment down into the threaded hole.
Great idea BTW.